feat: add issue template

.github/ISSUE_TEMPLATE/bug-report.md

@@ -0,0 +1,33 @@
+---
+name: Bug report
+about: Create a bug report about the GTK theme.
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is. 
+
+**Mention your distribution and your theme version**
+Please mention your Linux distribution and the theme version you've installed.
+
+**Select how you installed the theme**
+- [ ] GitHub Releases
+- [ ] AUR package 
+- [ ] Nixpkg
+- [ ] Using the python install script <!-- If you installed using the python script, please mention the command that you ran for installation. -->
+- [ ] Flatpak
+
+**Symlinked the gtk-4.0 folder?**
+Have you symlinked the `gtk-4.0` folder as mentioned in the [README](https://github.com/catppuccin/gtk/blob/e907775723eb68a5628c1bcd718b9d822cea9aee/README.md?plain=1#L85-L93)? **This is not applicable for users who have installed the theme with the Nix package.**
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If possible, please share screenshots of the bug you've encountered. 
+
+**Additional context**
+Please mention any additional context that might be applicable.